Regulator based on the control of a member having variable impedance surface-characteristics, particularly for feed adjustment in i.c. engines

ABSTRACT

A regulator, particularly for an internal combustion engine, includes a member with variable impedance surface characteristics, contacted by a tracer element. The member has such a material composition and distribution at its surface as to feature a varying impedance characteristic across its surface layer, the varying impedance characteristic representing the value of a function of two independently varying physical quantitites. The regulator has means to impart relative displacement between the member and the tracer element, in two different directions of the surface of the member, the magnitudes of the displacements being respectively proportional to the two independently varying physical quantities. The tracer element and the member are connected as part of an indicating circuit which senses the varying impedance characteristic depending on the changing point of contact betwen the tracer element and the member to give an output signal proportional to the value of the known function of the two independently varying physical quantities.

United States Patent 1191 Garcea 1 Feb. 12, 1974 [54] REGULATOR BASED ON THE CONTROL 2,442,630 6/1948 Wickesser 1. 338/14 OF A MEMBER HAVING VARIABLE 2,542,717 2/1951 Smith 338/14 1 2,877,326 3 1959 Bourns... 338/14 MPEDANCE 3,520,476 7/1970 Schmid 338/14 SURFACE-CHARACTERISTICS,

PARTICULARLY FOR FEED ADJUSTMENT- IN LC. ENGINES Inventor: Gian Paolo Garcea, Milan, Italy Assignee: Alfa Romeo S.p.A., Milan, ltaly Filed: May 24, 1972 Appl. No.: 256,511

Related U.S. Application Data Continuation-in-part of Ser. No. 856,432, Sept. 9, 1969, abandoned.

[30] Foreign Application Priority Data Sept. 14, 1968 Italy 21257/68 [52] U.S. Cl 323/82, 323/93, 323/94, 338/14 [51] Int. Cl HOlc 7/00 [58] Field of Search 338/14; 323/82, 93, 94

[56] References Cited UNITED STATES PATENTS 1,386,915 8/1921 Underhill v 73/518 1,855,333 4/1932 Borovec t 338/45 2,775,650 12/1956 Mason et al 179/100.1 B

Primary Examiner-L. T. Hix Attorney, Agent, or FirmJohn'C. Holman ct al.

[57] ABSTRACT A regulator, particularly for an internal combustion engine, includes a member with variable impedance surface characteristics, contacted by a tracer element. The member has such a material composition and distribution at its surface as to feature a varying impedance characteristic across its surface layer, the varying impedance characteristic representing the value of a function of two independently varying physical quantitites. The regulator has means to impart relative displacement between the member and the tracer element, in two different directions of the surface of the member, the magnitudes of the displacements being respectively proportional to the two independently varying physical quantities. The tracer element and the member are connected as part of an indicating circuit which senses the varying impedance characteristic depending on the changing point of contact betwen the tracer element and the member to give an output signal proportional to the value of the known function of the two independentlyvarying physical quantities.

8 Claims, 2 Drawing Figures REGULATOR BASED ON THE CONTROL OF A MEMBER HAVING VARIABLE IMPEDANCE SURFACE-CHARACTERISTICS, PARTICULARLY FOR FEED ADJUSTMENT IN I.C. ENGINES This Specification is a continuation-in-part of the US. Application Ser. No. 856,432, filed on Sept. 9, 1969, which is now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to regulators wherein a regulating signal is generated which is a function of two independently variable quantities which cannot conveniently be expressed as a simple mathematical function; in particular, this invention relates to a regulator for fuel feed adjustment in internal combustion engines, wherein the variable parameters are represented by the engine speed and the throttle displacement of the engine.

2. Description of Prior Art The necessity often arises in practice for a regulator in which a quantity C must be automatically furnished as a function of two other variable physical quantities A and B. Further, the two physical quantities A and B are often independent of one another and the physical quantity C cannot be expressed mathematically as a function of the quantities A and B.

Regulators are known which automatically furnish in such a case the value of the physical quantity C, being based on the use of a first mobile member in the form of a three dimensional cam which carries out movements with respect to a tracer member, which movements are proportional to the quantities A and B, while the tracer furnishes thephysical adjustment quantity C, it being moved in a direction normal to that of the two aforesaid movements in relation to the dimensions of the three dimensional cam in the direction normal to that of the movements which it undergoes because of the variations of the quantities A and B.

The opportunity may, however, arise of providing the physical quantity C in an electrical form, because of the advantages which may be derived from this from the point of view of the desired adjustment. With reference to this it has already been proposed to use a three dimensional cam as that described above, which carries out movements with respect to a tracer member whichmovements are proportional to the quantities A and B such that the tracer member is moved in a direction normal to the movements of the cam, utilising the movements of the tracer for controlling an electrical device forming part of an electrical adjustment circuit.

SUMMARY OF THE INVENTION The above described prior art arrangement has, however, the disadvantage that while accurate adjustment can be obtained, the constructional arrangement is complicated and uneconomical, since a threedimensional cam is provided besides the tracer member, and, the movement of the tracer member is used to actuate means such as a transducer forming part of an indicating circuit. A three-dimensional cam is dispensed with in the instant invention which uses a first member having a surface which is contacted by a tracer member. The first member has, in a preferred embodiment, two movements which are proportional to two independently varying physical quantities A and B. Alternatively, the first member may be given a displacement in one direction, proportional to a first independently varying physical quantity, and the tracer member may be given a displacement transverse to said one direction and proportional to the second independently varying physical quantity. By virtue of the resultant movement of the mobile member to a new position, the tracer member contacts the mobile member at a point different from the initial point of contact. The first member is characterized by its inherent material composition and a known distribution thereof and is advantageously constructed out of two layers of different material so that at different points of its effective thickness which may vary, the impedance characteristics, (e.g., the magnetic reluctance or the capacitance,) vary according to a known pattern. The physical arrangement between the tracer member and the mobile member is made part of a measuring/indicating circuit, e.g., electrical or magnetic so as to be able to measure an output quantity C which is a required function of said first two variables A and B. The invention as described above may be adapted to govern or regulate a fuel injection mechanism in an internal combustion engine. An output which is a combined function of the engine speed i.e., parameter A, and a throttle position, i.e., parameter B, may be combined to result in a signal provided by the varying impedance characteristic of the mobile member at the point of contact of between the tracer member and the first member as a known function of the parameters A and B, said signal being the output which may be used to govern the fuel injection in the engine.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the regulator according to this invention will now be described by way of example with reference to the accompanying drawing in which:

FIG. 1 is an axial sectional view of the regulator 1 FIG. 2 is a section through the line IIII of FIG. 1.

In the device illustrated the two variable physical v quantities A and B, as a function of which the physical adjustment quantity C is to be furnished electrically, are a rotational speed of an I.C. engine and an angular position of the throttle respectively.

DESCRIPTION OF PREFERRED EMBODIMENT The regulator consists essentially of a box ll, closed by a cover 2 inside which a centrifugal governing device is provided which is constituted by the cup 3 on whose toroidal internal surface the spheres 4 guidingly rotate, thrust by an entrainment member 5 entrained into rotation in its turn by the shaft 6 by means of a splined clutch which permits the entrainment member 5 to slide axially with respect to the shaft 6.

By way of an axial bearing 7 associated with the member 8, a spring 9 opposes the axial components of the centrifugal displatemen ts on the spheres 4 so that for each engine speed there is a different axial position of the members 5, 7 and 8 with respect to the shaft 6 and hence to the box 1 because the shaft 6 is set axially to the box by means of the bearings 10. The member 8 constituting the first member which, as mentioned before, takes the place of the three dimensional cam used in certain regulators of the mechanical type. The member 8 being linked to the entrainment member 5 by means of the bearing 7 can assume various angular 'positions according to the angular position of the external lever 11 keyed on to the shaft 12. The latter is capable of angular movement in the cover 2 and it entrains the member 8 by means of the rod 13 rigid with it, by way of a channel member 14. A separation line 15 between two materials which constitute the member 8 is visible in the upper part of the sectional view of the member 8 in FIG. 1. A spring 15 maintains one extremity of'a tracer member 17 in contact with the outer of the two materials constituting the member 8. The varying thickness of said materials between one point and another causes the electrical'tor magnetic) characteris tics to be different from point to point over the surface of the member 8. The member 17 is connected into the measuring-indicating circuit MC while the inner of the materials constituting the member 8 is also connected to the measuring-indicating circuit MC.

The member 8 in the embodiment described undergoes displacement in two different directions: the first displacement is proportional to the engine speed as imparted to the centrifugal sphere unit 4. This displacement is the axial component of the guided displacement of the spheres along the inner surface of the cup 3. The member 8 itself does not rotate, but is shifted in the direction of the cover 2. The second displacement of the member 8 is angular and is imparted thereto by the member 11 and is dependent on the position of the engine throttle. The combination of the two displacements shifts the point of contact of the tracer member 17 with the member 8 to a new point resulting in a different output of the impedance characteristic of the member 8 as the case may be. Members 17 and 8 as shown are connected as part of the circuit MC, and the changed impedance, e.g., electrical resistance at the new point of contact of the member 17 on member 8 can be measured readily to give a corresponding signal to the fuel injection system of the engine.

The measuring circuit MC measures at each instant the impedance across the thickness of the surface layer of the member 8 at the point of contact of the member 17 therewith, to give an output signal. The impedance across the thickness of the surface layer of the member 8 may be composed of electric resistance'or magnetic reluctance as described earlier, or may even be a capacitance; in any case, the material composition and distribution across the thickness of the surface layer of the member 8 is so arranged as to provide a required impedance variation pattern at various points of contact on the surface of the member 8. A suitable type of measuring circuit is used depending upon the nature of the impedanceof the surface layer of the member, i.e., depending upon whether it is an electrical resistance, or magnetic reluctance, or a capacitance. More particularly:

a. In case of a circuit of the resistance type, the said outer layer can be formed by a mixture, like that prepared by mixing metal powders and graphite; the inner layer, is formed by an electrically conductive material, such as copper.

b In case of a magnetic reluctance circuit the tracer member 17 is of a material having high magnetic permeability, and is part of a magnetic circuit closed on itself and comprising other parts, within the regulator, which are also formed by a material of high magnetic permeability; since the said circuit comprises also the outer thickness of the member 8 which is of a material having low magnetic permeability, e.g., a plastic material, this outer layer affects the total permeability ofthc said magnetic circuit and therefore any variation of the magnetic permeability of the circuit will be detected by a magnetic coil, the winding of which is linked with said circuit, provided that said coil is fed with ac current of sufficient frequency level.

c. In case ofa capacitive circuit, the outer layer of the member 8 is of a dielectric material, e.g., a plastic material, whereas the inner layer may be of copper; of course, the capacitance will be extremely reduced, since the thickness cannot be brought to infinitesimal values and the surface area of the tracer member 17 is quite small; however, by using sufficiently high freqeuncy levels a good performance, sensitivity and accuracy of the device can be ensured.

It is also to be noted in the present invention that on varying the location of the contact point between the member 8 and the tracer 17 by relative movement.

therebetween, the extension of the contact area does not change and therefore any contact uneveness with the related inaccuracies of the controlled quantity is avoided, since the contact surface of the member 8. is cylindrical and is not shaped with a variable profile.

The tracer member 17 may be kept stationary, if the member 8 is driven to effect displacements according to two directions, perpendicular to each other, as a function of the variations of the quantities A and B; al-

ternatively, according to a modification, the member 8 may be made to have a controlled displacement proportional to a first independently variable physical quantity, and the tracer member may be made to have a controlled displacement in a direction transverse to the displacement of member 8 and proportional to the second independently variable physical quantity.

What is claimed is:

l. A regulator producing a signal corresponding to a required combined function of first and second independently variable physical quantities, said regulator comprising a first member with a contact surface and an under surface and a predetermined material composition and distribution therebetween, said material composition and distribution inherently effecting varying'impedance characteristics at various points across and between said contact and under surfaces in accordance with said required combined function; a second tracer member mounted to contact and rest against said contact surface; and means to impart two relative movements between said first member and said second member in different directions, each of said relative movements being proportional to and controlled by said first and second independently variably physical quantities, and means effecting electrical connections from said first member and said second member whereby the first member and the second tracer memher are connected as part of an impedance. measuring and indicating circuit which gives out a signal corresponding to the combined function of said first and second independently variable physical quantities.

2. A regulator as claimed in claim 1, in which said impedance characteristics comprise electrical resistance.

3. A regulator as claimed in claim 1, in which said impedance characteristics comprise magnetic reluctance.

4. A regulator as claimed in claim 1, in which said impedance characteristics comprise capacitance.

member is generally of the shape of a hollow cylinder and said plate of constant thickness formed from said two super-imposed layers constitutes part of the cylinder periphery, on which part the second tracer member is disposed to rest and contact.

8. A regulator as claimed in claim 7, wherein said means effecting electrical connections includes connecting means electrically connecting the second tracer member and the first member in series in said impedance measuring and indicating circuit. 

1. A regulator producing a signal corresponding to a required combined function of first and second independently variable physical quantities, said regulator comprising a first member with a contact surface and an under surface and a predetermined material composition and distribution therebetween, said material composition and distribution inherently effecting varying impedance characteristics at various points across and between said contact and under surfaces in accordance with said required combined function; a second tracer member mounted to contact and rest against said contact surface; and means to impart two relative movements between said first member and said second member in different directions, each of said relative movements being proportional to and controlled by said first and second independently variably physical quantities, and means effecting electrical connections from said first member and said second member whereby the first member and the second tracer member are connected as part of an impedance measuring and indicating circuit which gives out a signal corresponding to the combined function of said first and second independently variable physical quantities.
 2. A regulator as claimed in claim 1, in which said impedance characteristics comprise electrical resistance.
 3. A regulator as claimed in claim 1, in which said impedance characteristics comprise magnetic reluctance.
 4. A regulator as claimed in claim 1, in which said impedance characteristics comprise capacitance.
 5. A regulator as claimed in claim 1, in which said first member comprises a plate of constant thickness formed from two superimposed layers of two different materials, a surface of separation between the superimposed layers varying in distance from said contact surface.
 6. A regulator as claimed in claim 5, wherein said means to impart said two relative movements includes a centrifugal governing mechanism to impart to the first member a spring biased linear displacement proportional to an engine speed.
 7. A regulator as claimed in claim 6, wherein the first member is generally of the shape of a hollow cylinder and said plate of constant thickness formed from said two super-imposed layers constitutes part of the cylinder periphery, on which part the second tracer member is disposed to rest and contact.
 8. A regulator as claimed in claim 7, wherein said means effecting electrical connections includes connecting means electrically connecting the second tracer member and the first member in series in said impedance measuring and indicating circuit. 